Broad Excitation Spectra between Crystalline-Electric-Field Levels Associated with Non-Kramers Doublet Ground State of f Electrons in PrNb2Al20

摘要

Inelastic neutron scattering measurements of PrNb2Al20, which exhibits non-Fermi-liquid behaviors, were carried out in order to determine the f-electron crystalline-electric-field split. Magnetic inelastic scattering intensities were observed at excitation energies of up to 15 meV, which are attributed to the crystalline-electric-field level scheme with the non-Kramers Gamma(3) doublet ground state of 4 f(2) in Pr3+ ions. The intrinsic full width at half maximum of the excitations from Gamma(3) to Gamma(5) and Gamma(4) are estimated to be approximately 3.7 meV. These values are much larger than those of the isomorphic PrTr2Zn20 (Tr = Rh and Ir). The considerably broad spectrum of PrNb2Al20 supports the existence of hybridization between Pr 4f electrons and conduction electrons, which mediates the Kondo effect in this material.